A068621 - OEIS

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A068621

a(1) = 7; a(n+1) = smallest triangular number > a(n) formed by adding at least one digit to a(n).

%I #8 Feb 11 2018 00:55:39

%S 7,78,378,1378,91378,7791378,707914378,3270729214378,

%T 183270773294214378,1783270773268946226147378

%N a(1) = 7; a(n+1) = smallest triangular number > a(n) formed by adding at least one digit to a(n).

%Y Cf. A068618, A068619, A068622, A068623, A068624.

%K base,nonn

%O 1,1

%A _Amarnath Murthy_, Feb 25 2002

%E a(5)-a(7) from _Ray G. Opao_, Dec 14 2004

%E a(8)-a(10) from _Max Alekseyev_, Apr 25 2009, Feb 11 2018